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PHBH26BS erratic idle

PostPosted: Mon Sep 15, 2014 5:17 pm
by denisiw
I've just read a post regarding PHBH carb float weights and I'm wondering if having a 9.5gm float in my PHBH26BS carb is the reason for me not being able to obtain a satisfactory idle with my Mugello 200 kitted SX200. My thinking being that when idling the heavier float is letting excess fuel into the float chamber which is in turn getting into the engine.

I started with a 50 pilot and had a black plug, I have gone right down to 32! I've now fitted a 35 again! I get it to idle but if I open the throttle slightly it 4-strokes. It then takes a while to settle down after it's been revved. It doesn't run fast, it races and is irratic. It's fitted with a RamAir filter and there are no air leaks.

Apart from the idling issue it goes well!

Does anyone agree with my supposition or am I barking up the wrong tree?

Cheers.

Denis

Re: PHBH26BS erratic idle

PostPosted: Mon Sep 15, 2014 5:31 pm
by St George
Is your choke seating properly ? 45 to 50 pilot seems right. I have a Ramair on mine, quite happy with it albeit runs better without it.
Regards Colin

Re: PHBH26BS erratic idle

PostPosted: Mon Sep 15, 2014 6:05 pm
by denisiw
St George wrote:Is your choke seating properly ? 45 to 50 pilot seems right. I have a Ramair on mine, quite happy with it albeit runs better without it.
Regards Colin

Yes it is.

Denis

Re: PHBH26BS erratic idle

PostPosted: Mon Sep 15, 2014 11:10 pm
by collector1967
I am thinking same Denis mine has the black 9.5 float, i have been told to go for a 6.5 i think.Will be needing a few parts soon Denis, will bell you.
Cheers Ian :)

Re: PHBH26BS erratic idle

PostPosted: Thu Sep 18, 2014 12:49 pm
by stonerosesmod
I have a small block mugello 200 with a 26mm PHBH and use a 53 pilot with a ram air filer,seems to be fine.Have you tried the mixture screw as well with the 50 pilot? Thinking it sounds like a choke issue or the float valve not seating properly?

Re: PHBH26BS erratic idle

PostPosted: Mon Sep 22, 2014 9:56 am
by denisiw
I've tried everything that I can think of.

Regarding the float weight; I spoke to someone at Eurocarb and was told that the black 9.5gm float has the same buoyancy as the white 6.5gm float, so I was barking up the wrong tree!

Denis